Using DOS Commands with MS-DOS 6.22

When you want your computer to perform an action, you communicate this request for service by entering commands at the DOS prompt. All DOS commands begin with a word, sometimes called a keyword, that identifies the action you want to take. Most DOS commands can accept parameters that refine the scope of the command, and adding parameters to this command enables you to specify exactly the files you want listed. In this chapter, learn the different elements of a DOS Command and how to issue them.

This sample chapter is excerpted from Special Edition Using MS-DOS 6.22, 3rd Edition.

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Understanding DOS Commands

When you want your computer to perform an action, you communicate this
request for service by entering commands at the DOS prompt. All DOS commands
begin with a word, sometimes called a keyword, that identifies the action
you want to take. Most DOS commands can accept parameters that refine the scope
of the command. The DIR command, for example, tells DOS to show you a
list of files written on a disk. Adding parameters to this command enables you
to specify exactly the files you want listed.

Internal Versus External

DOS recognizes and responds to more than 80 commands. The programming to
provide the most commonly used commands is contained within the DOS command
interpreter, COMMAND.COM. You use commands such as DIR and
COPY so frequently that making them available on demand whenever the
computer is displaying a DOS prompt saves time. Because DOS does not have to
launch (start) any program to provide the service, the commands provided
by COMMAND.COM are called internal commands. You can tell which
commands are internal by looking in the directory where DOS is installed. You
never find COPY.COM or COPY.EXE, so you know that the
COPY command is internal.

Other commands are stored as utility programs in a directory on your hard
disk. Because these commands are not built into the command processor, they are
called external commands. When you type a command that
COMMAND.COM does not recognize as one of its internal commands,
COMMAND.COM responds by looking on disk for a program file having the
same name as the command. The FORMAT command, for example, is provided
by programming found in the file FORMAT.COM, which is located in the
DOS directory.

Whether internal or external, all DOS commands conform to rules that provide
a grammar or syntax that is consistent throughout DOS. As a user, you need to
make sure only that DOS can find the program files for external commands.